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	<title></title>
	<script type="text/javascript">
		// 作业1：手动实现数组的concat方法

		// 作业2：数组求差集/交集/并集
		var arr1 = [1,2,3,4,5];
		var arr2 = [3,4,5,6,7];

		差集：[1,2,6,7]
		交集：[3,4,5]
		并集：[1,2,3,4,5,6,7]

		var newArr = [];
		(arr1.includes(arr2[3]) == false) => newArr.push(arr2[i])
		(arr2.includes(arr1[3]) == false) => newArr.push(arr1[i])
	</script>
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